Prolactin and dopamine concentrations in the cerebrospinal fluid during the neonatal period

Prolactin (PRL) has been detected in the cerebrospinal fluid (CSF) in humans and the absolute level appears to reflect the serum PRL concentration. Because PRL is thought to be involved in the regulation of brain water and electrolyte content attempt has been made to determine CSF and plasma PRL and dopamine (DA) concentrations, osmolality, and sodium level in 21 newborn infants undergoing lumbar punction because of apneic spells, fever, or perinatal asphyxia. The mean of gestational age was 36.5 weeks (range: 31-41) and birthweight was 2572 g (range: 1140-3550). The lumbar puncture was performed at the 8.3 postnatal day (range: 1-38). The plasma concentration of PRL was 106.52 +/- 14.43 ng/ml, significantly higher than the CSF PRL level (43.24 +/- 7.39 ng/ml, p < 0.01). This elevated level was observed in all individual cases. DA concentration in the plasma was much higher than the value detected in the CSF (64.75 +/- 13.83 vs 8.64 +/- 0.72 ng/ml, p < 0.01). No difference was observed between the sodium content of the CSF and plasma (138.94 +/- 1.28 vs 138.04 +/- 1.03 mmol/l), however, the osmolality of the plasma tended to be higher than the CSF osmolality (286.7 +/- 3.81 vs 276.76 +/- 2.19 mosm/kg, p < 0.05). In the CSF osmolality, PRL, DA, and sodium concentrations did not show any correlation.

in the CSF PRL probably does not play a primary role in controlling the osmolality and sodium content. PRL in CSF seems to be independent from CSF DA concentration.